Previously, warnings upon encountering a deprecated use `=` in
assignments, exports, and aliases would print a message without any
indication of where the offending `=` was. This diff adds a proper
`Warning` enum, and uses it to report context, as is done with
compilation and runtime errors.
Eventually, there will probably be a `crate` visibility specifier that
does the same thing as `pub(crate)`. This commit replaces `pub` with
`pub(crate)`, so when `crate` is available we can easily switch to it.
Just's dependency on brev was the cause of a
fairly deep branch of the transitive dependency
tree. To decrease build time and make the life of
packagers easier, this diff moves the functionality
that Just was using in Brev into Just itself, and
removes the dependency on Brev.
Fortunately, the only functionality that Just was
using was the output function and OutputError
enum, so this was easily done.
`env_var(key)` looks up the value of the environment variable with name `key`, aborting execution if it is not found.
`env_var_or_default(key, default)` looks up the value of the environment variable with name `key`, returning `default` if it is not found.
